1. Wednesday, September 26, 2012 Homework: p. 185 #31, 34, 43 & 44 (36-42 mentally)

2. §4.1 Triangles & Angles Definitions Equilateral Triangle All 3 sides are congruent. Isosceles Triangle At least 2 sides are congruent Scalene Triangle No sides are congruent. These are classifications by SIDES.

3. Definitions, continued. Acute Triangle All 3 angles are acute. Equiangular Triangle All 3 angles are congruent (is also acute). Right Triangle One right angle. Obtuse Triangle One obtuse angle. 70º 55º These are classifications by ANGLES.

4. More Definitions vertex A vertex is the point that connects the sides of the triangle.

5. More Definitions vertex Two sides with a common vertex are adjacent. adjacent sides

6. More Definitions Hypotenuse: the side of a right triangle that is opposite the right angle. hypotenuse Legs: adjacent sides that form the right angle in a right triangle. leg

7. More Definitions Base: the side of an isosceles triangle that is not (necessarily) congruent to the other two sides. base Legs: the congruent sides of an isosceles triangle. leg

8. Classify the triangle by its angles and its sides. 45º 60º 75º

9. Classify the triangle by its angles and its sides. 45º 90º 45º

10. How many degrees does a triangle have? How do you know?